When an individual is lost or trapped in a destroyed building, he or she rarely has cell phone coverage. The reasons for lack of cell phone coverage are many. For example, in remote areas where hikers, skiers, boaters, and the like typically become lost, there is often no network coverage. When a building has been destroyed by, for example, earthquake, fire, missile, grenade, bomb, hurricane, and the like, there is often attendant damage to portions of the network. Additionally, in the situation where a person is trapped within a building or under snow, they may not have cell phone coverage because of signal penetration issues.
Although it would be ideal to be able to locate lost or trapped people by making a connection with their cell phone, this has not been done in the past because you cannot bring the tower, so to speak, to the lost/trapped individual. With the evolution of small cells, however, there is more mobility for “the tower.” It is therefore desirable to use a mobile eNodeB to locate a lost or trapped individual.
This provisional application builds upon the architecture of a multi-RAT node that can be a mobile eNodeB used to locate trapped or lost individuals. Accordingly, the disclosure of the multi-RAT node and the mesh network in which it operates is included in this application to provide additional context.
Mesh networks have existed on the fringe of the IT world since the early 1980's. See generally Power Source Online, Mesh Networks, Kristin Masters March 2010. http://www.powersourceonline.com/magazine/2010/03/mesh-networks. Recent advancements in wireless technology have promoted further exploration of applications for mesh networks; they hold extensive promise for rich applications such as sensor networks. Id.
Typically, a wireless mesh network operates in a homogeneous fashion, meaning that the nodes within the network share certain traits enabling communication between them. An example of this could be a wireless mesh network operating on a Wi-Fi protocol.
Before there were wireless communications, telephone calls were placed over wired infrastructure. For wired telephony, there were different wire-line protocols, e.g., ATM and TDM, that the telephone exchanges sought to connect. One way to interconnect these disparate networks was to create gateways that could bridge together the different networks. Although these gateways provided a bridge between networks, it is not always possible for a gateway to transparently connect different nodes from different networks without needing to emulate missing features on one network or to suppress unique features from another. This gateway paradigm has been used in wireless technology as well, one example being a personal Wi-Fi portable access point that connects to the Internet using a 3G or 4G cellular data connection.
Recently, some have studied the benefits of connecting heterogeneous mesh networks. For example, You, L. et al., noted “One of the key issues is networking, which means to interconnect lots of networks, such as internet, cellular networks, wireless sensor networks (ZigBee), wireless-fidelity networks (Wi-Fi), social networks, etc.” FHMESH: A Flexible Heterogeneous Mesh Networking Platform, You, L. et al, IEEE Sixth International Conference on Mobile Ad Hoc and Sensor Networks, Dec. 20, 2010. This paper noted that finding an efficient way to interconnect these networks is an ongoing challenge in the Cyber Physical Systems field. Id. The authors of this paper designed a “platform utilize[ing] WMN technology to interconnect heterogeneous networks, and buil[t] gateways based on SDR technology.” Id.
Others who have sought to combine heterogeneous mesh networks have taken a similar tack. For example, heterogeneous interfaces for mesh networks typically consist of gateways that act as bridges between the two separate mesh networks. These gateways often employ Software Defined Radio “SDR” technologies. In effect, these gateways act as translators between the two disparate mesh networks. The individual nodes in the two disparate mesh networks, however, do not communicate directly with one another. They can only communicate via the gateway.
There are many benefits to creating heterogeneous mesh networks including increasing capacity without increasing costs. Increased capacity is desirable under many scenarios including in emergency situations such as the Sep. 11, 2001 attack on New York City, hurricanes Katrina and Sandy, and most recently, the Boston Marathon bombings. In the eleven-plus years that have transpired between the 9/11 events and the recent Boston Marathon bombing, there have been enormous advances made in wireless communications. Reliability and capacity have increased tremendously during that timeframe. But in emergency situations, cellular networks are still not able to handle the increased demand for telephone and data services.
“Toward the bottom of the list of disturbing aspects about Monday's bombing at the Boston Marathon was this: Cellular networks in the area almost immediately slowed down and, for periods of time, appeared to stop working altogether. Runners and their loved ones could not connect, and victims had trouble communicating with emergency responders. That frustrating scene has become familiar, evoking disasters from the September 11th attacks in 2001 to Hurricane Sandy in 2012. We rely on cell phones to run our lives, but they tend to be useless—or at least far from useful—when we need them most . . . . The science behind these failures in wireless connectivity isn't complicated. In every city, each mobile carrier operates hundreds or thousands of cell towers, which route calls and data to the carrier's backbone network. Each tower is designed to accommodate a set number of calls per second, per a certain geographic area. In a crisis, when everyone naturally reaches for their phone, that limit is quickly surpassed and the radios on the tower get sluggish. Mobile analyst Chetan Sharma, who estimates that a cell site can handle 150 to 200 calls per second per sector: ‘We've all had the experience of a fast-busy signal. That is the network telling you, “Sorry, but your cell is overloaded. There is no more space.” Brad Stone, Why Cell Phone Networks Fail in Emergencies, Bloomberg Businessweek Technology, Apr. 16, 2013. http://www.businessweek.com/articles/2013-04-16/why-cell-phone-networks-fail-in-emergencies
In order to increase capacity and utilize all possible resources presently available, it is desirable to create a heterogeneous mesh network where the nodes themselves provide the heterogeneity. If, for example, in the minutes after the bombing at the Boston Marathon, traffic had been rerouted, not to user's designated backhaul locations, but instead to backhaul locations that were geographically further away, e.g., Cambridge, South Boston, or Chelsea, there would have been more backhaul available on these networks to facilitate data transmission. The present invention addresses this need.